Programming Praxis

Today’s exercise is simple, but some languages make it hard:

Write a program that returns an input string with each space character in the string doubled. For instance, the string “hello hello” (with one space between the two words) is transformed to “hello  hello” (with two spaces between the two words).

That may not come out right in all browsers; here is the transformation again, with space characters replaced by plus signs for visibility, using a constant-space font:

"hello+hello" => "hello++hello"

Depending on your language, that might be an easy task, or a hard one. You may have to deal with memory allocation, or non-mutable strings, or appends that blow up to quadratic time.

Your task is to write a program that doubles the space characters in its input. When you are finished, you are welcome to read or run a suggested solution, or to post your own solution or discuss the exercise in the comments below.

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